1. Field of the Invention
The present invention relates to a vehicle-lamp lighting-on device for lighting a vehicle lamp e.g., a head lamp, attached thereto.
2. Description of the Related Art
A discharge lamp, e.g., a metal halide lamp, is used for a head lamp of a vehicle. The discharge lamp is detachably attached to a socket provided in the front of the vehicle. Electrodes of the discharge lamp are connected to the terminals of the socket. In this example, electric power is supplied from a power source through the socket terminals to the discharge lamp to light the lamp. The power source supplies voltage of about 400V to a lighting-on transformer. The transformer then boosts the voltage and produces a high voltage at the secondary coil thereof, and applies it to the socket terminals. The lighting-on transformer is provided outside the lamp housing having the socket therein. A high voltage cable is led out of the secondary terminal of the transformer, introduced into the lamp housing, and connected to the terminals of the socket.
Thus, the socket and the lighting-on transformer are separately located, and they are connected by the high voltage cable. The conventional vehicle-lamp lighting-on device has the following problems: 1) the number of required component parts is large; 2) mounting of those component parts is troublesome; 3) use of the high voltage cable restricts to design the components layout; 4) electromagnetic waves generated from the high voltage cable interferes with the electronic control circuitry located therearound, causing it to erroneously operate; 5) power loss is caused by the high voltage cable; and 6) others.
To solve the problems, there is proposed a vehicle-lamp lighting-on device having the following construction. A socket, which receives a discharge lamp, is attached to a body case and protrudes from one side of the body case. A lighting-on transformer is placed in the body case. In the transformer, a coil bobbin, made of insulating material, is wound by a secondary coil. A core housing includes an iron core formed therein. The coil bobbin is put in and fit to the iron core of the core housing.
The socket is inserted into the body case, and the lighting-on transformer is connected to the terminals of the socket within the body case. Therefore, the lighting-on device does not need the high voltage cable for connecting the lighting-on transformer and the socket.